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Cancer Risk due to Diagnostic Radiology

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Cancer Risk due to Diagnostic Radiology, CT-associated Radiation Exposure, Radiation Exposure in Medical Procedures, ALARA Principle of Radiation Exposure

  • Definition
  1. ALARA Principle of Radiation Exposure
    1. As low as reasonably achievable
    2. In some cases (e.g. serious Head Trauma), CT is needed (even in children)
  • Epidemiology
  1. Comparisons
    1. Standard Chest XRay (2 view) Radiation Exposure: 0.06 to 0.25 mSv
    2. Radiation from natural sources in an entire year (Germany): 2.4 mSv/year
    3. Survivors of Hiroshima and Nagasaki Atomic bombings: 50 to 150 mSv
    4. Mean lethal dose radiation (kills 50% population within 60 days): 3500 to 4000 mSv
  2. Occupational exposure restrictions (U.S. Dept Energy)
    1. Adult medical imaging worker radiation exposure limit: 50 mSv/year
    2. Pregnant worker radiation exposure limit: 5 mSv/year
  3. Pregnancy exposure risks
    1. Exposure <100 mSv: Low risk of fetal malformation
    2. Exposure >500 mSv: Moderate to high risk of fetal malformation
  4. Interpretation
    1. Cummulative exposure risk increases after age 40
    2. Medical Imaging may cause 1% of U.S. Cancers
    3. Each 1 mSv increase in exposure leads to 5 extra malignancies per 100,000 people
    4. Thyroid radiation exposure is proportionally much higher in Chest CT
    5. Diederich (2000) Cancer 89:2457-60 [PubMed]
  • Adverse Effects
  • Highest risk procedures (in descending order of risk)
  1. CT Scan (expecially CT Neck, CT Lung, CT Pelvis)
  2. Barium Enema
  3. Hip XRay
  4. Pelvis XRay
  • Adverse Effects
  • Cancers associated with Radiography
  • Adverse Effects
  • Plain Radiograph (XRay) radiation exposures
  1. Lumbar Spine 3-view series: 1.5 mSv
  2. Hip XRay: 0.7 mSv
  3. Abdominal XRay series: 0.7 mSv
  4. Mammogram: 0.2 mSv
  5. Chest XRay (PA and Lateral): 0.1 mSv
  6. DEXA Scan: 0.04 mSv
  7. Dental Panoramic XRay: 0.012 mSv
  • Adverse Effects
  • Radiation Exposure from Fluoroscopy
  1. Cardiac
    1. Coronary Angiography with stent placement: 13 mSv
    2. Electrophysiology study alone: 3.2 mSv
    3. Cardiac Catheter Ablation
      1. Atrial Tachycardia Ablation: 4.4 mSv
      2. Atrioventricular nodal reentrant Tachycardia (AVNRT) ablation: 4.8 mSv
      3. Atrial Flutter Ablation: 12.1 mSv
      4. Atrioventricular Reciprocating Tachycardia (AVRT) ablation: 12.8 mSv
      5. Atrial Fibrillation Ablation: 16.6 mSv
    4. References
      1. Efstathopoulos (2006) Europace 8(6): 443-8 [PubMed]
      2. Perisinakis (2001) Circulation 104(1): 58-62 [PubMed]
      3. Shapira (2009) Am Fam Physician 80(10): 1089-94 [PubMed]
  2. Abdomen
    1. TIPS Procedure: 70 mSv
    2. Pelvic vein embolization: 60 mSv
    3. Barium Enema: 8 mSv
    4. Intravenous pyelogram: 8 mSv
    5. Upper GI Series: 5 mSv
    6. ERCP: 4 mSv
  • Adverse Effects
  • CT-related Radiation Exposure
  1. CT Radiation Exposure (average, in MilliSieverts)
    1. High dose protocols: 3-27 mSv
    2. Low dose protocols: 0.3-0.55 mSv
  2. CT radiation exposure varies by CT type
    1. CT Electron beam (EBT): 11 mSv Chest, 26 mSv Abdomen
    2. CT Sequential: 4 mSv Chest, 20 mSv Abdomen
    3. CT Spiral: 2 mSv Chest, 7 mSv Abdomen
    4. Becker (1998) Radiologe 38:726-9 [PubMed]
  3. CT radiation exposure during episodic care (e.g. Trauma)
    1. Average radiation exposure during a Trauma admission: 22.7 mSv
      1. Tien (2007) j Trauma 62:151-6 [PubMed]
    2. CT Cervical Spine is associated with significant radiation exposure (especially to Thyroid Gland)
      1. Cervical Spine XRay: 0.24 to 0.51 mSv (for comparison)
      2. CT Cervical Spine radiation dose at Thyroid averages 64 mSv in age <18 years
        1. Thyroid Cancer excess Relative Risk is 13% for males and 25% for females
      3. Muchow (2012) J Trauma Acute Care Surg 72(2):403-9 [PubMed]
  4. CT Chest Radiation Exposures (in milliSieverts)
    1. Newborn: 1.7 mSv
    2. Five year old (on low dose CF protocol): 0.55 mSv
    3. Adults: 5.4 mSv
      1. Equivalent of 20 to 90 Chest XRays
    4. Huda (2007) Proc Am Thorac Surg 4:316-20 [PubMed]
  5. CT regional relative radiation exposures (may overestimate exposures)
    1. Head and Neck
      1. CT Head and Brain: 2 mSv
      2. CT Neck: 3 mSv
    2. Chest
      1. CT Chest Coronary Angiogram
        1. CT Calcium Score (performed prior to each CCTA): 3 to 4 mSv
        2. CCTA-64 slice with Retrospective Gating of diastole: 16 mSv in men and 23 mSv in women
        3. CCTA-64 slice with Prospective Gating of diastole: 10 mSv in men and 14 mSv in women
        4. CCTA-64 slice with Dual Source of diastole: 2 to 4 mSv
      2. CT Chest Pulmonary Angiogram (for PE): 15 mSv
      3. CT Chest: 10 mSv
      4. CT Calcium scoring: 3 to 4 mSv
    3. Abdomen
      1. CT Abdomen: 10 mSv
      2. CT Pelvis: 7 mSv
      3. CT Virtual Colonoscopy: 10 mSv
      4. Radiation induced sold-tumor risk in children
        1. Girls: 1 new cancer per 300-390 CT Abdomen and Pelvis
        2. Boys: 1 new cancer per 670-760 CT Abdomen and Pelvis
        3. Miglioretti (2013) JAMA Pediatr 167(8): 700-7 [PubMed]
    4. Spine
      1. CT Cervical Spine: 5 mSv
      2. CT Lumbar Spine: 7 mSv
  • Adverse Effects
  • Nuclear Medicine
  1. Cardiac
    1. Myocardial perfusion imaging with thalium: 29 mSv
    2. Myocardial perfusion imaging with sestamibi: 12 mSv
  2. Gastrointestinal
    1. Cholescintigraphy (e.g. HIDA Scan): 1-3 mSv
    2. Technetium 99m tagged Red Blood Cell study: 8 mSv
  3. Miscellaneous
    1. Bone Scan: 6 mSv
    2. Thyroid uptake scan: 2 mSv
    3. PET Scan: 14 mSv
  • Resources
  1. XRay Risk Calculator
    1. http://xrayrisk.com/